No, it wasn't. At least, anywhere other than Montana. The limits were higher, then Carter made then 55, nationally. Montana used to have "Safe and Reasonable"

No, it wasn't. At least, anywhere other than Montana. The limits were higher, then Carter made then 55, nationally. Montana used to have "Safe and Reasonable" as a daytime speed limit. During 55, it was forced to be that, but it was widely ignored and there was a $5 fine for "Excessively Utilizing Natural Resources". People would hold a $5 bill out the window when pulled over.